Single-component low-modulus epoxy pouring sealant and preparation method thereof

Abstract

The invention discloses a single-component low-modulus epoxy pouring sealant, which is prepared from the following raw materials in parts by weight: 80 to 200 parts of epoxy resin, 30 to 150 parts of curing agent, 100 to 600 parts of filler, 1 to 10 parts of accelerant, 1 to 14 parts of additive and 0.1 to 2 parts of pigment. The pouring sealant disclosed by the invention can be directly used, and double components do not need to be mixed when being used, so that the introduction of bubbles is avoided, and the uniformity and stability of the pouring sealant are improved. The composition has the advantages of low modulus, low curing temperature and short curing time, reduces curing conditions, and avoids the influence on electronic devices. Compared with the prior art, the pouring sealant has the advantages that the modulus after curing is relatively low, internal stress is favorably released, the phenomena of bulging, cracking, shelling and the like of the pouring sealant during long-time working or high-low temperature circulation are reduced, and the high-temperature stability and the elastic modulus can be balanced, so that the pouring sealant has more excellent high-low temperature resistance.

Description

Technical Field

[0001] This invention relates to the field of non-mechanical adhesives, specifically to a one-component low-modulus epoxy potting compound and its preparation method. Background Technology

[0002] Epoxy potting compounds play an irreplaceable role in the encapsulation and protection of electronic devices. However, traditional epoxy potting compounds are mostly two-component, requiring stirring and mixing during use, which can easily introduce air bubbles and result in uneven mixing, affecting the uniformity and integrity of the potting compound and reducing product reliability. Existing potting compounds have high hardness and high modulus after curing, making them prone to cracking in alternating hot and cold environments. Furthermore, excessively high temperatures during the curing process can cause irreversible damage to temperature-sensitive devices, affecting their lifespan. As electronic devices become increasingly integrated, heat accumulation during operation also affects the lifespan of the potting compounds. Therefore, developing a single-component, low-modulus, medium-to-low temperature curing, high thermal conductivity potting compound is crucial.

[0003] Chinese invention patent CN114806477B discloses a flexible epoxy potting compound, its preparation method, and its application. A toughening curing agent is prepared by reacting a thiol-alkene click reaction with a thiol compound under ultraviolet irradiation. The bisphenol A type epoxy resin potting compound cured with this toughening curing agent exhibits good crack resistance under drastic temperature changes, greatly improving the reliability of the encapsulated object. However, the two-component potting compound is prone to introducing air bubbles, causing uneven colloid composition. Chinese invention patent application CN119144258A discloses a high-temperature resistant, high-thermal-conductivity single-component epoxy potting compound and its preparation method. During the preparation of the epoxy potting compound, phenolic resin grafted epoxy resin and modified core-shell epoxy resin are added, along with a dicyandiamide curing agent, a phenyl-containing diluent, and thermally conductive powder. This significantly improves the thermal stability of the epoxy potting compound; however, the curing temperature is high, which may cause irreversible damage to temperature-sensitive devices. Summary of the Invention

[0004] In order to develop a one-component, low-modulus, medium-low temperature curing, high thermal conductivity potting compound, the first aspect of the present invention provides a one-component low-modulus epoxy potting compound, which is prepared by weight of raw materials including 80-200 parts of epoxy resin, 30-150 parts of curing agent, 100-600 parts of filler, 1-10 parts of accelerator, and 1-16 parts of additives.

[0005] In one embodiment, the raw materials prepared by weight include 100-150 parts of epoxy resin, 90-120 parts of curing agent, 300-500 parts of filler, 2-5 parts of accelerator, and 4-10 parts of additives.

[0006] In one embodiment, the raw materials prepared by weight include 100 parts epoxy resin, 90 parts curing agent, 500 parts filler, 2 parts accelerator, and 6.5 parts additives.

[0007] In one embodiment, the epoxy resin includes epoxy resin A and epoxy resin B. Epoxy resin A includes one or more of the following: bisphenol A type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, alicyclic epoxy resin, or aliphatic epoxy resin. Epoxy resin B includes one or more of the following: polyurethane modified epoxy resin, acrylic modified epoxy resin, silicone modified epoxy resin, core-shell toughened epoxy resin, rubber toughened epoxy resin, or nano-SiO2 modified epoxy resin.

[0008] In one embodiment, epoxy resin A includes at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and hydrogenated bisphenol A type epoxy resin; epoxy resin B includes at least one of polyurethane modified epoxy resin and core-shell toughened epoxy resin.

[0009] In one embodiment, epoxy resin A is bisphenol F type epoxy resin; epoxy resin B is core-shell toughened epoxy resin.

[0010] In one embodiment, the weight ratio of epoxy resin A to epoxy resin B is (2-10):1.

[0011] In one embodiment, the weight ratio of epoxy resin A to epoxy resin B is (1-5):1.

[0012] In one embodiment, the weight ratio of epoxy resin A to epoxy resin B is 4:1.

[0013] This invention employs a combination of bisphenol F epoxy resin and core-shell toughened epoxy resin. The bisphenol F epoxy resin provides the polymer curing framework, while the core-shell toughened epoxy resin pre-disperses toughening particles. The resulting resin crosslinking network exhibits excellent toughness, preventing cracking issues in high and low temperature cycling environments. At a preferred weight ratio, the bisphenol F epoxy resin and core-shell toughened epoxy resin achieve a low modulus while maintaining a low curing temperature and short curing time. However, when the core-shell toughened epoxy resin exceeds the preferred weight range, higher curing temperatures are required, increasing curing conditions and potentially damaging electronic devices, while also reducing structural strength.

[0014] In this application, the thiol curing agent reacts with the epoxy resin to form a three-dimensional network structure. The introduction of sulfur atoms and the ester bonds in the thiol curing agent molecules provide more degrees of freedom of movement, which helps to improve the elasticity and toughness of the final cured material, reduce the modulus of the potting compound after curing, facilitate the release of internal stress, and reduce the occurrence of blistering, cracking, and peeling of the potting compound during long-term operation or high and low temperature cycling.

[0015] In one embodiment, the curing agent is a thiol curing agent with a functionality of 2-4.

[0016] As one embodiment, the thiol curing agent includes at least a thiol curing agent with a functionality of 4.

[0017] As one embodiment, the thiol curing agent with a functionality of 4 includes at least one of pentaerythritol tetramercaptoacetate, pentaerythritol tetrakis(3-mercaptopropionic acid) ester, trimethylolpropane tri(3-mercaptopropionic acid) ester, or pentaerythritol tetrakis(3-mercaptobutyric acid) ester.

[0018] As one embodiment, the thiol curing agent further includes a thiol curing agent with a functionality of 2-3.

[0019] As one embodiment, the thiol curing agent with a functionality of 2-3 includes at least one of ethylene glycol dimercaptoacetate, ethylene glycol dimercaptopropionate, or 1,4-butanediol di(3-mercaptobutyrate).

[0020] In one embodiment, the weight ratio of the thiol curing agent with a functionality of 4 to the thiol curing agent with a functionality of 2-3 is (1-10):1.

[0021] In one embodiment, the weight ratio of the thiol curing agent with a functionality of 4 to the thiol curing agent with a functionality of 2-3 is (5-10):1.

[0022] In one embodiment, the weight ratio of the thiol curing agent with a functionality of 4 to the thiol curing agent with a functionality of 2-3 is 8:1.

[0023] This invention employs a combination of a 4-functionality thiol curing agent and a 2-3-functionality thiol curing agent. The 4-functionality thiol curing agent provides a high crosslinking density with its high functionality structure, ensuring high-temperature stability. The 2-3-functionality thiol curing agent provides linear segments with better mobility after curing, reducing the modulus. Under a preferred weight ratio, it balances high-temperature stability and elastic modulus, thereby exhibiting superior high and low temperature resistance.

[0024] In one embodiment, the accelerator includes one or a combination of several of imidazole, imidazole derivatives, modified fatty amines, dicyandiamide derivatives, aromatic amines, and tertiary ammonium salt accelerators.

[0025] In one implementation, the promoter is a latent fatty amine promoter.

[0026] This invention employs a latent fatty amine accelerator that does not significantly promote the curing reaction of epoxy resin at room temperature, but can be rapidly activated under heating or other specific conditions to accelerate the curing process. It can remain liquid during manufacturing and storage, and then be rapidly cured by heating when in use, thereby improving the processing convenience and mechanical properties of the material.

[0027] In one embodiment, the additives include one or a combination of coupling agents, defoamers, stabilizers or thixotropic agents.

[0028] In one embodiment, the additives, by weight, include 0.5-2 parts coupling agent, 0.5-2 parts defoamer, 0.1-5 parts stabilizer, 0.1-5 parts thixotropic agent, and 0.1-2 parts pigment.

[0029] In one embodiment, the additives, by weight, include 1 part coupling agent, 1 part defoamer, 2 parts stabilizer, 1 part thixotropic agent, and 1.5 parts pigment.

[0030] As one embodiment, the coupling agent includes, but is not limited to, at least one of 2-(3,4-epoxycyclohexyl)ethoxysilane, 3-glycidylpropyltrimethoxysilane, 3-glycidylpropylmethyldiethoxysilane, 3-glycidylpropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropylmethyldiethoxysilane, or phthalate coupling agents.

[0031] In one embodiment, the defoamer includes, but is not limited to, at least one of polyoxyethylene glycerol ester, polyoxypropylene glycerol ester, polyoxyethylene monobutyl ester, polydimethylsiloxane, or polymethylphenylsiloxane.

[0032] As one implementation, the stabilizer includes, but is not limited to, at least one of salicylic acid, barbituric acid, stearic acid, lauric acid, or fumaric acid.

[0033] In one embodiment, the thixotropic agent includes, but is not limited to, fumed silica.

[0034] In one embodiment, the pigment includes, but is not limited to, at least one of carbon black, titanium dioxide, toluidine red, iron oxide red, phthalocyanine blue, or phthalocyanine green.

[0035] In one embodiment, the filler includes one or a combination of several of the following: alumina, magnesium oxide, zinc oxide, aluminum nitride, boron nitride, silicon micropowder, or silicon carbide.

[0036] A second aspect of the present invention provides a method for preparing a one-component low-modulus epoxy potting compound, comprising the following steps:

[0037] Dehydrate the epoxy resin and stir it evenly at room temperature; add the curing agent, coupling agent, defoamer, stabilizer, thixotropic agent, pigment, and filler in sequence, stir evenly at room temperature, cool to room temperature, add the accelerator, control the temperature at 20-25℃, degas, and obtain epoxy potting compound.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] (1) The single-component low-modulus epoxy potting compound of the present invention can be used directly without the need for two-component mixing, thus avoiding the introduction of air bubbles and improving the uniformity and stability of the potting compound.

[0040] (2) The single-component low-modulus epoxy potting compound of the present invention uses a combination of bisphenol F type epoxy resin and core-shell toughened epoxy resin. The rigid structure such as benzene ring provides excellent structural strength of the potting compound. The polar groups such as hydroxyl groups at the end of the cured end and ether bonds in the chain segment ensure that the potting compound can form good adhesion with various material shells.

[0041] (3) The single-component low-modulus epoxy potting compound of the present invention uses a weight ratio of (2-10):1 for bisphenol F type epoxy resin and core-shell toughened epoxy resin. It has low modulus and low curing temperature and short curing time, which reduces curing conditions and avoids the impact on electronic devices.

[0042] (4) The single-component low-modulus epoxy potting compound of the present invention reacts with epoxy resin and mercaptan curing agent, which helps to improve the elasticity and toughness of the final cured material, reduce the modulus of the potting compound after curing, and help to release internal stress and reduce the occurrence of blistering, cracking and peeling of the potting compound during long-term operation or high and low temperature cycles.

[0043] (5) The single-component low-modulus epoxy potting compound of the present invention uses a combination of a 4-functionality thiol curing agent and a 2-3-functionality thiol curing agent, which can balance high temperature stability and elastic modulus, thus having better high and low temperature resistance. Detailed Implementation

[0044] Example 1

[0045] A single-component low-modulus epoxy potting compound, prepared by weight, comprises 100 parts epoxy resin, 90 parts curing agent, 500 parts filler, 2 parts accelerator, 1 part coupling agent, 1 part defoamer, 2 parts stabilizer, 1 part thixotropic agent, and 1.5 parts pigment.

[0046] The epoxy resin comprises epoxy resin A and epoxy resin B in a weight ratio of 4:1. Epoxy resin A is a bisphenol F type epoxy resin, purchased from Wuhan Xinyang Ruihe Chemical Technology Co., Ltd., with the grade NPEF-170; epoxy resin B is a core-shell toughened epoxy resin, purchased from Kaneka Corporation, Japan, with the grade Kane. MX-125.

[0047] The curing agent is a thiol curing agent, comprising a thiol curing agent with a functionality of 4 and a thiol curing agent with a functionality of 2, in a weight ratio of 8:1; the thiol curing agent with a functionality of 4 is pentaerythritol tetramercaptoacetate, and the thiol curing agent with a functionality of 2 is ethylene glycol dimercaptoacetate.

[0048] The filler is spherical alumina, purchased from Henan Tianma New Material Co., Ltd., with the grade TM-QW-50.

[0049] The accelerator is a latent aliphatic tertiary amine, purchased from Shanghai Jintaino Materials Technology Co., Ltd., with the brand name JTN-200.

[0050] The coupling agent is 3-glycidylpropyltrimethoxysilane.

[0051] The defoamer is polydimethylsiloxane, purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd., brand name DB95968.

[0052] The stabilizer is barbituric acid, the thixotropic agent is fumed silica, and the pigment is carbon black.

[0053] A method for preparing a one-component low-modulus epoxy potting compound includes the following steps:

[0054] Dehydrate the epoxy resin and stir it evenly at room temperature; add the curing agent, coupling agent, defoamer, stabilizer, thixotropic agent, pigment, and filler in sequence, stir evenly at room temperature, cool to room temperature, add the accelerator, control the temperature at 24℃, degas, and obtain epoxy potting compound.

[0055] Example 2

[0056] A single-component low-modulus epoxy potting compound and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that the raw materials prepared by weight include 100 parts of epoxy resin, 90 parts of curing agent, 300 parts of filler, 2 parts of accelerator, 1 part of coupling agent, 1 part of defoamer, 2 parts of stabilizer, 1 part of thixotropic agent, and 1.5 parts of pigment.

[0057] Example 3

[0058] A single-component low-modulus epoxy potting compound and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that the curing agent is a combination of pentaerythritol tetramercaptoacetate and 1,4-butanediol di(3-mercaptobutyrate) ester in a weight ratio of 5:1.

[0059] Example 4

[0060] A single-component low-modulus epoxy potting compound and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that the epoxy resin B is a polyurethane modified epoxy resin purchased from Shanghai Kaiyin Chemical Co., Ltd., with the grade EPU-133L.

[0061] Example 5

[0062] A single-component low-modulus epoxy potting compound and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that the accelerator is an imidazole derivative, purchased from Shanghai Jintaino Materials Technology Co., Ltd., with the brand name JTN-30.

[0063] Comparative Example 1

[0064] A single-component low-modulus epoxy potting compound and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that the raw materials prepared by weight include 100 parts of epoxy resin, 130 parts of curing agent, 500 parts of filler, 2 parts of accelerator, 1 part of coupling agent, 1 part of defoamer, 2 parts of stabilizer, 1 part of thixotropic agent, and 1.5 parts of pigment.

[0065] The curing agent is methyltetrahydrophthalic anhydride.

[0066] Comparative Example 2

[0067] A single-component low-modulus epoxy potting compound and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that the accelerator is 2,4,6-tris(dimethylaminomethyl)phenol.

[0068] Comparative Example 3

[0069] A single-component low-modulus epoxy potting compound and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that the raw materials prepared by weight include 100 parts of epoxy resin, 100 parts of curing agent, 500 parts of filler, 2 parts of accelerator, 1 part of coupling agent, 1 part of defoamer, 2 parts of stabilizer, 1 part of thixotropic agent, and 1.5 parts of pigment.

[0070] The epoxy resin includes epoxy resin A, which is a bisphenol F type epoxy resin purchased from Wuhan Xinyang Ruihe Chemical Technology Co., Ltd., with the brand name NPEF-170.

[0071] Comparative Example 4

[0072] A single-component low-modulus epoxy potting compound and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that the raw materials prepared by weight include 100 parts of epoxy resin, 60 parts of curing agent, 500 parts of filler, 2 parts of accelerator, 1 part of coupling agent, 1 part of defoamer, 2 parts of stabilizer, 1 part of thixotropic agent, and 1.5 parts of pigment.

[0073] The epoxy resin comprises epoxy resin A and epoxy resin B in a weight ratio of 3:7. Epoxy resin A is a bisphenol F type epoxy resin, purchased from Wuhan Xinyang Ruihe Chemical Technology Co., Ltd., with the grade NPEF-170; epoxy resin B is a core-shell toughened epoxy resin, purchased from Kaneka Corporation of Japan, with the grade Kane. MX-125.

[0074] Comparative Example 5

[0075] A single-component low-modulus epoxy potting compound and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that the raw materials prepared by weight include 100 parts of epoxy resin, 90 parts of curing agent, 500 parts of filler, 2 parts of accelerator, 1 part of coupling agent, 1 part of defoamer, 2 parts of stabilizer, 1 part of thixotropic agent, and 1.5 parts of pigment.

[0076] The curing agent is pentaerythritol tetramercaptoacetate.

[0077] Performance testing

[0078] The test methods for the epoxy potting compounds prepared in the examples and comparative examples are shown in Table 1.

[0079] Table 1

[0080]

[0081]

[0082] Note: The potting period is the time it takes for the viscosity of the potting compound to double at the corresponding temperature. Test results are shown in Tables 2 and 3.

[0083] Table 2

[0084]

[0085] Table 3

[0086]

[0087]

[0088] Examples 1-5 are potting compounds that meet the requirements of being single-component, low-modulus, requiring medium-to-low temperature curing, and exhibiting high thermal conductivity. They possess high thermal conductivity (≥0.95 W / (K·m), elastic modulus ≤200 MPa, and hardness ≤80 HA, significantly lower than Comparative Example 1. This allows for better release of internal stress, preventing cracking under heat and stress, and improving resistance to thermal shock. Examples 1-5 pass thermal shock tests, while the potting compound in Comparative Example 1 cracks and fails. Furthermore, the curing temperature of these examples is only 80°C, compared to 120°C in Comparative Examples 1 and 4. 100°C is more suitable for temperature-sensitive components such as semiconductor devices, microtransistors, and plastic encapsulation elements, and also saves energy costs in production. Additionally, compared to Comparative Example 2, these examples significantly extend the room temperature potting life, greatly improving product stability during production, transportation, and storage.

[0089] In Comparative Example 1, the curing agent was replaced with methyltetrahydrophthalic anhydride instead of thiol curing agent. Compared with Example 1, the curing temperature was higher, the modulus was higher, and the hardness was greater, but it could not pass the thermal shock test.

[0090] The accelerator in Comparative Example 2 was non-latent 2,4,6-tris(dimethylaminomethyl)phenol; compared with Example 1, it had a shorter room temperature pot life and poorer stability, and was not practical for production preparation.

[0091] Comparative Example 3 used only the base resin epoxy resin A: bisphenol F type epoxy resin; compared with Example 1, it has a higher modulus and greater hardness, and cannot pass the thermal shock test.

[0092] In Comparative Example 4, the epoxy resin B was increased to 70 parts by weight in excess. Compared with Example 1, the curing temperature was higher and the curing time was longer, and it could not pass the thermal shock test.

[0093] Comparative Example 5, using only a tetrafunctional thiol curing agent, failed the thermal shock test compared to Example 1.

[0094] The thermal conductivity of the embodiments and comparative examples in this application is ≥0.95W / (K·m), indicating that the selected thermally conductive fillers, coupling agents, etc., when used in combination within the mass range described herein, can achieve good filler dispersion, form a dense heat conduction network, and achieve good thermal conductivity.

Claims

1. A one-component low-modulus epoxy potting compound, characterized in that, The raw materials prepared by weight include 80-200 parts of epoxy resin, 30-150 parts of curing agent, 100-600 parts of filler, 1-10 parts of accelerator, and 1-16 parts of additives.

2. The single-component low-modulus epoxy potting compound according to claim 1, characterized in that, The epoxy resin includes epoxy resin A and epoxy resin B. Epoxy resin A includes one or more of the following: bisphenol A type epoxy resin, bisphenol F type epoxy resin, hydrogenated bisphenol A type epoxy resin, alicyclic epoxy resin, or aliphatic epoxy resin. Epoxy resin B includes one or more of the following: polyurethane modified epoxy resin, acrylic modified epoxy resin, silicone modified epoxy resin, rubber toughened epoxy resin, or nano-SiO2 modified epoxy resin.

3. The single-component low-modulus epoxy potting compound according to claim 2, characterized in that, The weight ratio of epoxy resin A to epoxy resin B is (2-10):

1.

4. The single-component low-modulus epoxy potting compound according to claim 1, characterized in that, The curing agent is a thiol curing agent with a functionality of 2-4.

5. The single-component low-modulus epoxy potting compound according to claim 4, characterized in that, The thiol curing agent includes at least a thiol curing agent with a functionality of 4.

6. The single-component low-modulus epoxy potting compound according to claim 5, characterized in that, The thiol curing agent also includes a thiol curing agent with a functionality of 2-3, and the weight ratio of the thiol curing agent with a functionality of 4 to the thiol curing agent with a functionality of 2-3 is (1-10):

1.

7. The single-component low-modulus epoxy potting compound according to claim 1, characterized in that, The accelerator includes one or a combination of several of imidazole, imidazole derivatives, modified fatty amines, dicyandiamide derivatives, aromatic amines, or tertiary ammonium salt accelerators.

8. The single-component low-modulus epoxy potting compound according to claim 1, characterized in that, The additives include one or a combination of coupling agents, defoamers, stabilizers, thixotropic agents, or pigments.

9. The single-component low-modulus epoxy potting compound according to claim 1, characterized in that, The filler includes one or a combination of several of the following: alumina, magnesium oxide, zinc oxide, aluminum nitride, boron nitride, silicon micro powder, or silicon carbide.

10. A method for preparing a single-component low-modulus epoxy potting compound according to any one of claims 8-9, characterized in that, Includes the following steps: Dehydrate the epoxy resin and stir it evenly at room temperature; add curing agent, coupling agent, defoamer, stabilizer, thixotropic agent, pigment and filler, stir evenly at room temperature, cool to room temperature and add accelerator, control the temperature at 20-25℃, degas, and obtain epoxy potting compound.

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